Advanced Data Processing Inc. is not disclosing the number of patients affected by a breach of ambulance billing information from the Covington Fire Department in Kentucky, but acknowledges the number is more than 500 and the HHS Office for Civil Rights has been notified.

The company learned on Oct. 1 that an employee was inappropriately accessing the billing system and disclosing information to a theft ring, which is believed to have used the information to file fraudulent federal tax returns. Compromised information included names, dates of birth and Social Security numbers.